Manufacture of sodium bicarbonate



,steps of preparing an aqueous solution of sothe suspension.

carbonate monohydrate employed as the starting 50 Patented Feb. 13, 1945 r MANUFACTURE OF SODIUM BICARBONATE Walter McGeorge,. Kingston Hill, and Francis Highland Milner, Twickenham, England, assignors to MacLeans Limited, Brentford Middlesex, England, a British company No Drawing. 7 Application September 29, 1942, Serial No. 460,166. In Great Britain October 22, 1941 i a r UNITED; STATESPATENT OFFICE I 10.Claims. (Cl. 2364) This invention relates to the manufacture of by-product in the process described in British sodium bicarbonate in a very fine state of divi- Specification No. 532,300. r i r x l The carbon dioxide may be passed into the sus- British Specification No. 532,301 describes a pension in a closed vessel under pressure with process for the preparation of sodium bicarbonate vigorous mechanical agitation, or it may be adin a very fine state of division, comprising the mixed with air and circulated vigorously through dium bicarbonate containing not less than Bgrams The sodium bicarbonate obtained according to preferably at a raised temperature not exceeding 10 moval of the alcohol or other organic liquid by The process of British specificationibio. 532,301, of sodium carbonate will be retained in theliq manufacture. a a r a that the resulting sodiumbicarbonate conforms It is an object of the present invention to to the standard or the British Pharmacopaeia. vide an improved process for th manufa tur of The following example illustrates ho-w the proc sodium bicarbonate in a very fine state of dl'vjess of the invention may be carried into effect. S1011, avoidin the dilution of the alcohol crrh 53 p rts y w i ht f finely ground sodi m like with water and consequently avoiding t carbonate (anhydrous B. P.) are suspended in 430 subsequent recovery by distillation of the alcohol pa ts by weight of industrial alcohol to which or the like. 20 parts by weight of water have been added With this object in View the present invention The mixture is stirred vigorously and Subjected provides a process for th manufa tu of to the action of carbon dioxide gas at a presdium bicarbonate in a very fin tat of 3 sure of four inches of water. This gives, after sion wherein anhydrous sodium carbonate or sofiltration and drying a 94% yield Sodium dium carbonate monohydrate is suspended in an carbonate in a Very fine State ofdivision and W organic liquid in which anhydrous sodium car tantially free from carbonate, r i w: bonate, sodium carbonate monohydrate and 50- In the example the quantity of Water added dium bicarbonate are substantially insoluble and may be increased up to mls. l r subjected to the action of carbon dioxide atat- We claim: l mospheric or increased pressure, the reaction 15A process for the manufacture of sodium being carried out n t presenc f Water, the bicarbonate in a very fine state of division comtemperature during t f u being prising the steps of suspending a substance setained below 40 C. The minimum quantit of 0 lected from the group comprising anhydrous sos when using alcohol the Strength Show of carbon dioxide in the presence of water and at l i The anhydrous sodium carbonate or sodium l and maintaining dium carbonate and sodium carbonate bicarbonate in a very ter and at a pressure not less than atmospheric, the temperature below 40 C. during the reaction. 7

-3. A process for the manufacture of sodium bicarbonate in a very fine state of division cornprising the steps of suspending a substance selected from the group comprising anhydrous sodium carbonate and sodium carbonate monohydrate in aqueous alcohol of a strength not less than 70%, subjecting the suspension to the action of carbon dioxide at a pressure not less than atmospheric, and maintaining the temperature below 40 C. during the reaction."

4. A process for the manufacture of sodium bicarbonate in a very fine state of division comprising the steps of suspending a substance-selected from the group comprising anhydrous sodium carbonate and sodium carbonate monohydrate in an organic liquid in which the said substance and sodiumbicarbonate are substantiallyinsoluble, subjecting the suspension to the action of carbon dioxide in 'thepresence of water and at a pressure not less than atmospheric until the sodium carbonate is completesconverted maintaining the temperature below 40 C. drir ing the reaction, separating the resulting sodium bicarbonate from the liquid by filtration,

and drying the separated sodium bicarbonate at atemperature below 40 C. a

'5. A process for the manufacture of sodium bicarbonate in a very fin state of division comprising the steps of suspending a substance selected from the group comprising anhydrous somonohydrate in alcohol, subjecting thesuspension to the action of carbon dioxide in the presence of water andat a pressure not less than atmospheric until the.'sodium carbonate is completely converted maintaining the temperature below 40 C. during the reaction, separating the resulting sodium bicarbonate from the liquid by filtration, and drying the separated sodium bicarbonate at 'a tem- ,perature below 40 C. I

6. Aprocess for the manufacture of sodium bicarbonatein a very fine state of division comprising the steps of suspending a substance selected from the group comprising'anhydroussodium carbonate and sodium carbonate monohydrate in aqueous alcohol or a strength not less than 70%, subjecting the suspension to the action of carbon dioxide at apressure not less than atmospheric. until the sodium carbonate is completely converted maintaining the temperature be1'ow40 C. during the reaction, separating the resulting sodium bicarbonate fromrthe liquid'by' nitration, carbonate at -a temperature below 40 and drying the separated sodium bi- 7. A process for the manufacture of sodium fine stateof division comreaction,

bicarbonate in a very action of carbon "insoluble, subjecting the suspension 'to the action of carbon dioxide in a pressure not less sodium carbonate is completely converted maintaining the temperature below 40 C. during the separating the resulting sodium bicar bonate from the liquid by filtration, washing the the presence of water and at separated sodium bicarbonate with alcohol and drying the separated sodium bicarbonate at a temperature below 40 C.

-8. A process for the 'manufacture of sodium fine state of division comsteps of suspending a substance segroup comprising anhydrous soand sodium carbonate monohysubjecting the suspension to the dioxide in the presence of water not less than atmospheric until prising the lected from the dium carbonate drate in alcohol,

and at a pressure the sodium carbonate is completely converted maintaining the temperature below 40 C. during the reaction, separating the resulting sodium biby filtration, washing: the separated sodium bicarbonate with alcohol,

carbonate from the liquid and drying the separated sodium bica bonate at a temperature below 40C.

9. A process for the manufacture of sodium bicarbonate in a very fine state of division comprising the steps of susp n a su stance s lected from the group comprising anhydrous sodium carbonate and sodium carbonate-monohydrate in aqueous alcohol of a strength not less than subjecting the suspension to the action of carbon dioxid ata pressure atmospheric until the sodium carbonate is completely converted maintaining the temperature below 40 C. during the reaction, separating the resulting sodium bicarbonate from the liquid by filtration, washing the separated sodium bicarbonate with alcohol, and drying the separated sodium bicarbonate at a temperature below 40C.

10. A process for the manufacture of sodium bicarbonate in a very fine state of division, comprising the steps'ofsuspendi-ng53 parts by weight of pharmaceutically pure anhydrou'ssodiumcar- .bonate in 450 parts by weight of aqueous alcohol consisting of 430 (parts of industrial alcohol and 20 parts of water, subjecting the suspension to vigorous stirring and to the action of gaseous carbondioxide under pressure until the sodium carbonate is completely converted, filtering to separate the liquid from the'solid phase, and-dryingthe separated sodium bicarbonate.

- WALTER MCGEORGE. FRANCIS HIGHLAND than atmospheric until the i not less than V 

